I dont have idea of Karachi market but as per me Exi Manual would be 850-950. Considering the mileage 850 or 9 lacks would be good for this car.
If the car has No work needed at all then i think one should Go for it because
1) its a Manual you will not face any problem regarding transmission
2) If its a well maintained car(maintained by authorized dealer) every thing is done on time and the plus point is that its Run on petrol i dont think it will give you any problems.
If you know the owner you can trust his word on the condition then.
but you can FIND an Exi or Vti manaul/prosmetic in very good condition in your budged of 12.